In general, the dehumidifier reduces humidity of a room by drawing humid air from the room, making the humid air to pass through a heat exchanger having a condenser and an evaporator through which refrigerant flows to remove moisture from the air, and discharging the air having the moisture removed therefrom, again.
That is, the dehumidifier takes heat from air around it by vaporizing liquid refrigerant at the evaporator. In more detail, a temperature of the evaporator drops as the refrigerant vaporizes, and as the air passes through the evaporator, a temperature of the air also drops.
As the temperature around the evaporator drops, the moisture in the air condenses, to form dew on a surface of the evaporator.
FIG. 1 illustrates a diagram of a related art dehumidifier.
Referring to FIG. 1, the related art dehumidifier is provided with a cabinet 1 having an inlet (not shown) for drawing room air, a filter 2 mounted on an inlet side, a heat exchanger 3 in front of the filter 2 on the cabinet 1 for heat exchange with the room air to dehumidify the room air, a fan assembly 4 in front of the heat exchanger 3 for forced circulation of the room air, a water tank 6 under the heat exchanger for collecting condensed water, and a front panel 5, a frontal exterior of the dehumidifier, having an outlet 5a. 
However, the related art dehumidifier has the following problems.
The outlet 5a in the front panel 5 provides a poor outer appearance, and is difficult to change a direction of discharge of the air.
Since the water tank 6 can be mounted/dismounted through a rear of the cabinet 1, the mounting/dismounting of the water tank 6 is not convenient.
Because the room air passed through the heat exchanger 3 is discharged to the room again directly even if the moisture is not removed from the air fully, the dehumidifying efficiency is poor.
Moreover, the use of the compressor in the related art humidifier for circulation of the refrigerant leads to a production cost high, and causes much noise and vibration during operation.